/*
MQUnifiedsensor Library - calibrating an MQ2 to MQ9
Demonstrates the use a MQ2 sensor.
Library originally added 01 may 2019
by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
Added example
modified 27 May 2019
by Miguel Califa
Wiring:
https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/static/img/MQ_Arduino.PNG
Please take care, arduino A0 pin represent the analog input configured on #define pin
This example code is in the public domain.
*/
//Include the library
#include <MQUnifiedsensor.h>
/************************Hardware Related Macros************************************/
#define Board ("Arduino Mega")
#define Pin2 (A2) //Analog input 2 of your arduino
#define Pin3 (A3) //Analog input 3 of your arduino
#define Pin4 (A4) //Analog input 4 of your arduino
#define Pin5 (A5) //Analog input 5 of your arduino
#define Pin6 (A6) //Analog input 6 of your arduino
#define Pin7 (A7) //Analog input 7 of your arduino
#define Pin8 (A8) //Analog input 8 of your arduino
#define Pin9 (A9) //Analog input 9 of your arduino
/***********************Software Related Macros************************************/
#define RatioMQ2CleanAir (9.83) //RS / R0 = 9.83 ppm
#define RatioMQ3CleanAir (60) //RS / R0 = 60 ppm
#define RatioMQ4CleanAir (4.4) //RS / R0 = 4.4 ppm
#define RatioMQ5CleanAir (6.5) //RS / R0 = 6.5 ppm
#define RatioMQ6CleanAir (10) //RS / R0 = 10 ppm
#define RatioMQ7CleanAir (27.5) //RS / R0 = 27.5 ppm
#define RatioMQ8CleanAir (70) //RS / R0 = 70 ppm
#define RatioMQ9CleanAir (9.6) //RS / R0 = 9.6 ppm
#define ADC_Bit_Resolution (10) // 10 bit ADC
#define Voltage_Resolution (5) // Volt resolution to calc the voltage
#define Type ("Arduino Mega 2560") //Board used
/*****************************Globals***********************************************/
//Declare Sensor
MQUnifiedsensor MQ2(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin2, Type);
MQUnifiedsensor MQ3(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin3, Type);
MQUnifiedsensor MQ4(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin4, Type);
MQUnifiedsensor MQ5(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin5, Type);
MQUnifiedsensor MQ6(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin6, Type);
MQUnifiedsensor MQ7(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin7, Type);
MQUnifiedsensor MQ8(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin8, Type);
MQUnifiedsensor MQ9(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin9, Type);
void setup() {
//Init serial port
Serial.begin(9600);
//init the sensor
MQ2.init();
MQ2.setRegressionMethod(1); //_PPM = a*ratio^b
MQ2.setA(574.25); MQ2.setB(-2.222); // Configurate the ecuation values to get LPG concentration
MQ2.setR0(9.659574468);
MQ3.init();
MQ3.setRegressionMethod(1); //_PPM = a*ratio^b
MQ3.setA(0.3934); MQ3.setB(-1.504); // Configurate the ecuation values to get Alcohol concentration
MQ3.setR0(3.86018237);
MQ4.init();
MQ4.setRegressionMethod(1); //_PPM = a*ratio^b
MQ4.setA(1012.7); MQ4.setB(-2.786); // Configurate the ecuation values to get CH4 concentration
MQ4.setR0(3.86018237);
MQ5.init();
MQ5.setRegressionMethod(1); //_PPM = a*ratio^b
MQ5.setA(97124); MQ5.setB(-4.918); // Configurate the ecuation values to get Alcohol concentration
MQ5.setR0(71.100304);
MQ6.init();
MQ6.setRegressionMethod(1); //_PPM = a*ratio^b
MQ6.setA(2127.2); MQ6.setB(-2.526); // Configurate the ecuation values to get CH4 concentration
MQ6.setR0(13.4285714);
MQ7.init();
MQ7.setRegressionMethod(1); //_PPM = a*ratio^b
MQ7.setA(99.042); MQ7.setB(-1.518); // Configurate the ecuation values to get CO concentration
MQ7.setR0(4);
MQ8.init();
MQ8.setRegressionMethod(1); //_PPM = a*ratio^b
MQ8.setA(976.97); MQ8.setB(-0.688); // Configurate the ecuation values to get H2 concentration
MQ8.setR0(1);
MQ9.init();
MQ9.setRegressionMethod(1); //_PPM = a*ratio^b
MQ9.setA(1000.5); MQ9.setB(-2.186); // Configurate the ecuation values to get LPG concentration
MQ9.setR0(9.42857143);
/***************************** MQ CAlibration ********************************************/
// Explanation:
// In this routine the sensor will measure the resistance of the sensor supposing before was pre-heated
// and now is on clean air (Calibration conditions), and it will setup R0 value.
// We recomend execute this routine only on setup or on the laboratory and save on the eeprom of your arduino
// This routine not need to execute to every restart, you can load your R0 if you know the value
// Acknowledgements: https://jayconsystems.com/blog/understanding-a-gas-sensor
Serial.print("Calibrating please wait.");
float MQ2calcR0 = 0,
MQ3calcR0 = 0,
MQ4calcR0 = 0,
MQ5calcR0 = 0,
MQ6calcR0 = 0,
MQ7calcR0 = 0,
MQ8calcR0 = 0,
MQ9calcR0 = 0;
for(int i = 1; i<=10; i ++)
{
//Update the voltage lectures
MQ2.update();
MQ3.update();
MQ4.update();
MQ5.update();
MQ6.update();
MQ7.update();
MQ8.update();
MQ9.update();
MQ2calcR0 += MQ2.calibrate(RatioMQ2CleanAir);
MQ3calcR0 += MQ2.calibrate(RatioMQ3CleanAir);
MQ4calcR0 += MQ2.calibrate(RatioMQ4CleanAir);
MQ5calcR0 += MQ2.calibrate(RatioMQ5CleanAir);
MQ6calcR0 += MQ2.calibrate(RatioMQ6CleanAir);
MQ7calcR0 += MQ2.calibrate(RatioMQ7CleanAir);
MQ8calcR0 += MQ2.calibrate(RatioMQ8CleanAir);
MQ9calcR0 += MQ2.calibrate(RatioMQ9CleanAir);
Serial.print(".");
}
MQ2.setR0(MQ2calcR0/20);
MQ3.setR0(MQ3calcR0/20);
MQ4.setR0(MQ4calcR0/20);
MQ5.setR0(MQ5calcR0/20);
MQ6.setR0(MQ6calcR0/20);
MQ7.setR0(MQ7calcR0/20);
MQ8.setR0(MQ8calcR0/20);
MQ9.setR0(MQ9calcR0/20);
Serial.println(" done!.");
Serial.print("Valores de R0 para cada sensor (MQ2 - MQ9):");
Serial.print(MQ2calcR0/10); Serial.print(" | ");
Serial.print(MQ3calcR0/10); Serial.print(" | ");
Serial.print(MQ4calcR0/10); Serial.print(" | ");
Serial.print(MQ5calcR0/10); Serial.print(" | ");
Serial.print(MQ6calcR0/10); Serial.print(" | ");
Serial.print(MQ7calcR0/10); Serial.print(" | ");
Serial.print(MQ8calcR0/10); Serial.print(" | ");
Serial.print(MQ9calcR0/10); Serial.println(" |");
if(isinf(MQ2calcR0) || isinf(MQ3calcR0) || isinf(MQ4calcR0) || isinf(MQ5calcR0) || isinf(MQ6calcR0) || isinf(MQ7calcR0) || isinf(MQ8calcR0) || isinf(MQ9calcR0)) {Serial.println("Warning: Conection issue founded, R0 is infite (Open circuit detected) please check your wiring and supply"); while(1);}
if(MQ2calcR0 == 0 || MQ3calcR0 == 0 || MQ4calcR0 == 0 || MQ5calcR0 == 0 || MQ6calcR0 == 0 || MQ7calcR0 == 0 || MQ8calcR0 == 0 || MQ9calcR0 == 0){Serial.println("Warning: Conection issue founded, R0 is zero (Analog pin with short circuit to ground) please check your wiring and supply"); while(1);}
/***************************** MQ CAlibration ********************************************/
//Print in serial monitor
Serial.println("MQ2 to MQ9 - lecture");
Serial.println("*************************** Lectures from MQ-board ***************************");
Serial.println("| LPG | Alcohol | CH4 | Alcohol | CH4 | CO | H2 | LPG |");
Serial.println("| MQ-2 | MQ-3 | MQ-4 | MQ-5 | MQ-6 | MQ-7 | MQ-8 | MQ-9 |");
//pinMode(calibration_button, INPUT);
}
void loop() {
//Update the voltage lectures
MQ2.update();
MQ3.update();
MQ4.update();
MQ5.update();
MQ6.update();
MQ7.update();
MQ8.update();
MQ9.update();
//Read the sensor and print in serial port
float MQ2Lecture = MQ2.readSensor();
float MQ3Lecture = MQ3.readSensor();
float MQ4Lecture = MQ4.readSensor();
float MQ5Lecture = MQ5.readSensor();
float MQ6Lecture = MQ6.readSensor();
float MQ7Lecture = MQ7.readSensor();
float MQ8Lecture = MQ8.readSensor();
float MQ9Lecture = MQ9.readSensor();
Serial.print("| "); Serial.print(MQ2Lecture);
Serial.print(" | "); Serial.print(MQ3Lecture);
Serial.print(" | "); Serial.print(MQ4Lecture);
Serial.print(" | "); Serial.print(MQ5Lecture);
Serial.print(" | "); Serial.print(MQ6Lecture);
Serial.print(" | "); Serial.print(MQ7Lecture);
Serial.print(" | "); Serial.print(MQ8Lecture);
Serial.print(" | "); Serial.print(MQ9Lecture);
Serial.println("|");
}